There has been known a sensor apparatus that measures properties of a liquid which is an analyte, or ingredients of a liquid, using a detection element such as a surface acoustic wave element (refer to Patent Literatures 1 to 3, for example).
For example, a sensor apparatus incorporating a surface acoustic wave element, which is constructed by disposing, on a piezoelectric substrate, a detection portion which reacts with a component contained in an analyte sample, is designed to detect properties or ingredients of a liquid which is an analyte by measuring variations in surface acoustic waves propagating through the detection portion. Such a measurement method using a surface acoustic wave element or the like has the advantage over other measurement methods (for example, enzyme method) in that it is adapted for a plurality of detection systems.
However, each conventional sensor apparatus incorporating a detection element such as a surface acoustic wave element in itself is devoid of a mechanism capable of fluid suction. Thus, to allow an analyte to flow into the detection portion, a procedural step of sucking the analyte using an instrument such as a micro pipette, and delivering the sucked analyte into the detection portion is required. This leads to an increase in the complexity of measurement operation. Furthermore, the placement of extra instruments as required results in scale-up of the measurement apparatus as a whole.
There is also known a sensor apparatus which adopts a different detection method from the detection method using a detection element such as a surface acoustic wave element. In this construction, a reagent containing, for example, an enzyme is applied in advance to a measuring electrode, and an analyte is caused to react with the applied reagent for the reading of changes in electric current in the measuring electrode (refer to Patent Literature 4).
In Patent Literature 4, there is disclosed a technique that enables the sensor apparatus in itself to effect suction of an analyte by exploiting capillary phenomenon. According to this technique, a narrow elongate analyte supply path is led out to the reagent-bearing part of the measuring electrode to wick an analyte so that it can be directed to the reagent-bearing part under capillary phenomenon.
Inconveniently, the analyte measurement method as disclosed in Patent Literature 4 that involves application of a reagent containing an enzyme or the like to the measuring electrode does not lend itself to examination on a plurality of items because of limitations upon the number of measurable examination items.
In the sensor apparatus described in Patent Literature 4, its measuring section is formed by applying a reagent to an electrode, wherefore the thickness of the measuring section is equivalent to the thickness of the electrode, that is; the measuring section is very thin. This allows the narrow analyte supply path to be elongated without discontinuity to the measuring section.
On the other hand, in the sensor apparatus incorporating a detection element such as a surface acoustic wave element, the detection element is constructed of, for example, a piezoelectric substrate, and thus has a certain thickness. In this case, even if the technology disclosed in Patent Literature 4 is applied, the analyte supply path may be obstructed by the detection element, thus making it difficult to pass an analyte to the detection portion.